Hilo, the Flex D rate and a local-first home: what fits together

What Hilo actually does

Hilo pairs with Hydro-Québec's Flex D rate. On the coldest winter days, Hydro-Québec announces peak events, typically morning and early evening. During those hours, the Hilo app lowers your thermostats by an amount you chose in advance, and you earn a credit for the electricity you did not use. The rest of the winter, the rate is slightly cheaper than the standard one; during peak hours, it is much more expensive, which is why the thermostats do the reducing for you.

The gateway that runs this is offered at no cost and is the centre of the Hilo experience. Hilo's own thermostats connect to it over Zigbee, and they work only with electric baseboards and convectors, not with central heating.

Which thermostats qualify

Hilo's compatibility list includes its own thermostats and certain models from three other makers: Honeywell Home for central heating, Mysa, and Sinopé. Not every model from those brands is included, so check the list before buying. Sinopé's Zigbee floor-heating thermostat is a notable case: it pairs directly to the Hilo gateway rather than through Sinopé's own hub.

The two things to understand

• A Zigbee device joins one network. A Hilo thermostat paired to the Hilo gateway belongs to that gateway, not to the hub that runs the rest of your home. It can still be seen from your hub through Hilo's cloud, but its control path is not local.
• Third-party thermostats join Hilo through the maker's account. A Mysa or Sinopé Wi-Fi thermostat keeps its own features, including Apple Home where supported, and receives the peak-event reductions through its cloud link to Hilo. That means the challenges depend on the internet being up, which for a few hours a few times a winter is an acceptable trade.

A sensible way to combine them

Keep your heating decisions local for the other three hundred and fifty days. Use line-voltage thermostats that talk to the hub in your home, so schedules, window sensors and presence rules keep working without the internet. Then enrol the compatible thermostats in Hilo for the peak events. On challenge days, Hilo lowers the setpoints; your hub sees the new setpoints and leaves them alone. Nothing else in the house, from the water valve to the lights, ever depends on the Hilo gateway.

Is it worth it?

That depends on how much of your heat is electric, how much you can tolerate a cooler house at 7 a.m. in January, and how many thermostats you have. Hydro-Québec publishes the credit amounts and the rate schedule, and both change. We run the numbers with you during the survey rather than quote a figure here that will be wrong next winter.